mdw@git.distorted.org.uk Git - tripe/blob - pkstream/pkstream.c

   1 /* -*-c-*-
   2  *
   3  * Forwarding UDP packets over a stream
   4  *
   5  * (c) 2003 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Trivial IP Encryption (TrIPE).
  11  *
  12  * TrIPE is free software: you can redistribute it and/or modify it under
  13  * the terms of the GNU General Public License as published by the Free
  14  * Software Foundation; either version 3 of the License, or (at your
  15  * option) any later version.
  16  *
  17  * TrIPE is distributed in the hope that it will be useful, but WITHOUT
  18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  20  * for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with TrIPE.  If not, see <https://www.gnu.org/licenses/>.
  24  */
  25
  26 /*----- Header files ------------------------------------------------------*/
  27
  28 #include "config.h"
  29
  30 #include <ctype.h>
  31 #include <errno.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35
  36 #include <sys/time.h>
  37 #include <sys/types.h>
  38 #include <unistd.h>
  39 #include <fcntl.h>
  40 #include <sys/uio.h>
  41 #include <sys/socket.h>
  42 #include <netinet/in.h>
  43 #include <arpa/inet.h>
  44 #include <netdb.h>
  45
  46 #include <mLib/alloc.h>
  47 #include <mLib/bits.h>
  48 #include <mLib/darray.h>
  49 #include <mLib/dstr.h>
  50 #include <mLib/fdflags.h>
  51 #include <mLib/mdwopt.h>
  52 #include <mLib/quis.h>
  53 #include <mLib/report.h>
  54 #include <mLib/sel.h>
  55 #include <mLib/selpk.h>
  56
  57 #include "util.h"
  58
  59 /*----- Data structures ---------------------------------------------------*/
  60
  61 typedef union addr {
  62   struct sockaddr sa;
  63   struct sockaddr_in sin;
  64 } addr;
  65
  66 DA_DECL(addr_v, addr);
  67 DA_DECL(str_v, const char *);
  68
  69 typedef struct pk {
  70   struct pk *next;                      /* Next packet in the chain */
  71   octet *p, *o;                         /* Buffer start and current posn */
  72   size_t n;                             /* Size of packet remaining */
  73 } pk;
  74
  75 typedef struct pkstream {
  76   unsigned f;                           /* Flags... */
  77 #define PKF_FULL 1u                     /*   Buffer is full: stop reading */
  78   sel_file r, w;                        /* Read and write selectors */
  79   pk *pks, **pk_tail;                   /* Packet queue */
  80   size_t npk, szpk;                     /* Number and size of data */
  81   selpk p;                              /* Packet parser */
  82 } pkstream;
  83
  84 typedef struct connwait {
  85   unsigned f;                           /* Various flags */
  86 #define cwf_port 1u                     /*   Port is defined => listen */
  87   sel_file *sfv;                        /* Selectors */
  88   addr_v me, peer;                     /* Who I'm meant to be; who peer is */
  89 } connwait;
  90
  91 /*----- Static variables --------------------------------------------------*/
  92
  93 static sel_state sel;
  94 static connwait cw;
  95 static int fd_udp;
  96 static size_t pk_nmax = 128, pk_szmax = 1024*1024;
  97
  98 /*----- Main code ---------------------------------------------------------*/
  99
 100 static int nonblockify(int fd)
 101   { return (fdflags(fd, O_NONBLOCK, O_NONBLOCK, 0, 0)); }
 102
 103 static int cloexec(int fd)
 104   { return (fdflags(fd, 0, 0, FD_CLOEXEC, FD_CLOEXEC)); }
 105
 106 static socklen_t addrsz(const addr *a)
 107 {
 108   switch (a->sa.sa_family) {
 109     case AF_INET: return sizeof(a->sin);
 110     default: abort();
 111   }
 112 }
 113
 114 static const char *addrstr(const addr *a)
 115 {
 116   static char buf[128];
 117   socklen_t n = sizeof(buf);
 118
 119   if (getnameinfo(&a->sa, addrsz(a), buf, n, 0, 0, NI_NUMERICHOST))
 120     return ("<addrstr failed>");
 121   return (buf);
 122 }
 123
 124 static int addreq(const addr *a, const addr *b)
 125 {
 126   if (a->sa.sa_family != b->sa.sa_family) return (0);
 127   switch (a->sa.sa_family) {
 128     case AF_INET:
 129       return (a->sin.sin_addr.s_addr == b->sin.sin_addr.s_addr);
 130     default:
 131       abort();
 132   }
 133 }
 134
 135 static void initaddr(addr *a)
 136 {
 137   a->sin.sin_family = AF_INET;
 138   a->sin.sin_addr.s_addr = INADDR_ANY;
 139   a->sin.sin_port = 0;
 140 }
 141
 142 #define caf_addr 1u
 143 #define caf_port 2u
 144 static void copyaddr(addr *a, const struct sockaddr *sa, unsigned f)
 145 {
 146   const struct sockaddr_in *sin;
 147
 148   a->sa.sa_family = sa->sa_family;
 149   switch (sa->sa_family) {
 150     case AF_INET:
 151       sin = (const struct sockaddr_in *)sa;
 152       if (f&caf_addr) a->sin.sin_addr = sin->sin_addr;
 153       if (f&caf_port) a->sin.sin_port = sin->sin_port;
 154       break;
 155     default:
 156       abort();
 157   }
 158 }
 159
 160 static void dolisten(void);
 161
 162 static void doclose(pkstream *p)
 163 {
 164   pk *pk, *ppk;
 165   close(p->w.fd);
 166   close(p->p.reader.fd);
 167   selpk_destroy(&p->p);
 168   if (!(p->f&PKF_FULL)) sel_rmfile(&p->r);
 169   if (p->npk) sel_rmfile(&p->w);
 170   for (pk = p->pks; pk; pk = ppk) {
 171     ppk = pk->next;
 172     xfree(pk->p);
 173     xfree(pk);
 174   }
 175   xfree(p);
 176   if (cw.f&cwf_port) dolisten();
 177   else exit(0);
 178 }
 179
 180 static void rdtcp(octet *b, size_t sz, pkbuf *pk, size_t *k, void *vp)
 181 {
 182   pkstream *p = vp;
 183   size_t pksz;
 184
 185   if (!sz) { doclose(p); return; }
 186   pksz = LOAD16(b);
 187   if (pksz + 2 == sz) {
 188     DISCARD(write(fd_udp, b + 2, pksz));
 189     selpk_want(&p->p, 2);
 190   } else {
 191     selpk_want(&p->p, pksz + 2);
 192     *k = sz;
 193   }
 194 }
 195
 196 static void wrtcp(int fd, unsigned mode, void *vp)
 197 {
 198 #define NPK 16
 199   struct iovec iov[NPK];
 200   pkstream *p = vp;
 201   size_t i;
 202   ssize_t n;
 203   pk *pk, *ppk;
 204
 205   for (i = 0, pk = p->pks; i < NPK && pk; i++, pk = pk->next) {
 206     iov[i].iov_base = pk->o;
 207     iov[i].iov_len = pk->n;
 208   }
 209
 210   if ((n = writev(fd, iov, i)) < 0) {
 211     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 212     moan("couldn't write to TCP socket: %s", strerror(errno));
 213     doclose(p);
 214     return;
 215   }
 216
 217   p->szpk -= n;
 218   for (pk = p->pks; n && pk; pk = ppk) {
 219     ppk = pk->next;
 220     if (pk->n <= n) {
 221       p->npk--;
 222       n -= pk->n;
 223       xfree(pk->p);
 224       xfree(pk);
 225     } else {
 226       pk->n -= n;
 227       pk->o += n;
 228       break;
 229     }
 230   }
 231   p->pks = pk;
 232   if (!pk) { p->pk_tail = &p->pks; sel_rmfile(&p->w); }
 233   if ((p->f&PKF_FULL) && p->npk < pk_nmax && p->szpk < pk_szmax)
 234     { p->f &= ~PKF_FULL; sel_addfile(&p->r); }
 235 }
 236
 237 static void rdudp(int fd, unsigned mode, void *vp)
 238 {
 239   octet buf[65536];
 240   ssize_t n;
 241   pkstream *p = vp;
 242   pk *pk;
 243
 244   if ((n = read(fd, buf, sizeof(buf))) < 0) {
 245     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
 246       return;
 247     moan("couldn't read from UDP socket: %s", strerror(errno));
 248     return;
 249   }
 250   pk = xmalloc(sizeof(*pk));
 251   pk->next = 0;
 252   pk->p = xmalloc(n + 2);
 253   STORE16(pk->p, n);
 254   memcpy(pk->p + 2, buf, n);
 255   pk->o = pk->p;
 256   pk->n = n + 2;
 257   *p->pk_tail = pk;
 258   p->pk_tail = &pk->next;
 259   if (!p->npk) sel_addfile(&p->w);
 260   sel_force(&p->w);
 261   p->npk++;
 262   p->szpk += n + 2;
 263   if (p->npk >= pk_nmax || p->szpk >= pk_szmax)
 264     { sel_rmfile(&p->r); p->f |= PKF_FULL; }
 265 }
 266
 267 static void dofwd(int fd_in, int fd_out)
 268 {
 269   pkstream *p = xmalloc(sizeof(*p));
 270   sel_initfile(&sel, &p->r, fd_udp, SEL_READ, rdudp, p);
 271   sel_initfile(&sel, &p->w, fd_out, SEL_WRITE, wrtcp, p);
 272   selpk_init(&p->p, &sel, fd_in, rdtcp, p);
 273   selpk_want(&p->p, 2);
 274   p->pks = 0;
 275   p->pk_tail = &p->pks;
 276   p->npk = p->szpk = 0;
 277   p->f = 0;
 278   sel_addfile(&p->r);
 279 }
 280
 281 static void doaccept(int fd_s, unsigned mode, void *p)
 282 {
 283   int fd;
 284   addr a;
 285   socklen_t sz = sizeof(a);
 286   size_t i, n;
 287
 288   if ((fd = accept(fd_s, &a.sa, &sz)) < 0) {
 289     if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR) return;
 290     moan("couldn't accept incoming connection: %s", strerror(errno));
 291     return;
 292   }
 293   n = DA_LEN(&cw.peer);
 294   if (!n) goto match;
 295   for (i = 0; i < n; i++) if (addreq(&a, &DA(&cw.peer)[i])) goto match;
 296   moan("rejecting connection from %s", addrstr(&a));
 297   close(fd); return;
 298 match:
 299   if (nonblockify(fd) || cloexec(fd)) {
 300     moan("couldn't accept incoming connection: %s", strerror(errno));
 301     close(fd); return;
 302   }
 303   dofwd(fd, fd);
 304   n = DA_LEN(&cw.me);
 305   for (i = 0; i < n; i++) { close(cw.sfv[i].fd); sel_rmfile(&cw.sfv[i]); }
 306 }
 307
 308 static void dolisten1(const addr *a, sel_file *sf)
 309 {
 310   int fd;
 311   int opt = 1;
 312
 313   if ((fd = socket(a->sa.sa_family, SOCK_STREAM, IPPROTO_TCP)) < 0 ||
 314       setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) ||
 315       bind(fd, &a->sa, addrsz(a)) ||
 316       listen(fd, 1) || nonblockify(fd) || cloexec(fd))
 317     die(1, "couldn't set up listening socket: %s", strerror(errno));
 318   sel_initfile(&sel, sf, fd, SEL_READ, doaccept, 0);
 319   sel_addfile(sf);
 320 }
 321
 322 static void dolisten(void)
 323 {
 324   size_t i, n;
 325
 326   n = DA_LEN(&cw.me);
 327   for (i = 0; i < n; i++)
 328     dolisten1(&DA(&cw.me)[i], &cw.sfv[i]);
 329 }
 330
 331 static void pushaddrs(addr_v *av, const struct addrinfo *ailist)
 332 {
 333   const struct addrinfo *ai;
 334   size_t i, n;
 335
 336   for (ai = ailist, n = 0; ai; ai = ai->ai_next) n++;
 337   DA_ENSURE(av, n);
 338   for (i = DA_LEN(av), ai = ailist; ai; ai = ai->ai_next) {
 339     initaddr(&DA(av)[i]);
 340     copyaddr(&DA(av)[i++], ai->ai_addr, caf_addr | caf_port);
 341   }
 342   DA_EXTEND(av, n);
 343 }
 344
 345 #define paf_parse 1u
 346 static void parseaddr(const struct addrinfo *aihint,
 347                       const char *host, const char *svc, unsigned f,
 348                       struct addrinfo **ai_out)
 349 {
 350   char *alloc = 0, *sep;
 351   int err;
 352
 353   if (f&paf_parse) {
 354     alloc = xstrdup(host);
 355     if ((sep = strchr(alloc, ':')) == 0)
 356       die(1, "missing port number in address `%s'", host);
 357     host = alloc; *sep = 0; svc = sep + 1;
 358   }
 359
 360   err = getaddrinfo(host, svc, aihint, ai_out);
 361   if (err) {
 362     if (host && svc) {
 363       die(1, "failed to resolve hostname `%s', service `%s': %s",
 364           host, svc, gai_strerror(err));
 365     } else if (host)
 366       die(1, "failed to resolve hostname `%s': %s", host, gai_strerror(err));
 367     else
 368       die(1, "failed to resolve service `%s': %s", svc, gai_strerror(err));
 369   }
 370
 371   xfree(alloc);
 372 }
 373
 374 static void usage(FILE *fp)
 375 {
 376   pquis(fp,
 377         "Usage: $ [-l PORT] [-b ADDR] [-p ADDR] [-c ADDR:PORT]\n\
 378         ADDR:PORT ADDR:PORT\n");
 379 }
 380
 381 static void version(FILE *fp)
 382   { pquis(fp, "$, tripe version " VERSION "\n"); }
 383
 384 static void help(FILE *fp)
 385 {
 386   version(fp);
 387   fputc('\n', fp);
 388   usage(fp);
 389   fputs("\n\
 390 Options:\n\
 391 \n\
 392 -h, --help              Display this help text.\n\
 393 -v, --version           Display version number.\n\
 394 -u, --usage             Display pointless usage message.\n\
 395 \n\
 396 -l, --listen=PORT       Listen for connections to TCP PORT.\n\
 397 -p, --peer=ADDR         Only accept connections from IP ADDR.\n\
 398 -b, --bind=ADDR         Bind to ADDR before connecting.\n\
 399 -c, --connect=ADDR:PORT Connect to IP ADDR, TCP PORT.\n\
 400 \n\
 401 Forwards UDP packets over a reliable stream.  By default, uses stdin and\n\
 402 stdout; though it can use TCP sockets instead.\n\
 403 ", fp);
 404 }
 405
 406 int main(int argc, char *argv[])
 407 {
 408   unsigned f = 0;
 409   str_v bindhosts = DA_INIT, peerhosts = DA_INIT;
 410   const char *bindsvc = 0;
 411   addr bindaddr;
 412   const char *connhost = 0;
 413   struct addrinfo aihint = { 0 }, *ai, *ailist;
 414   int fd = -1;
 415   int len = 65536;
 416   size_t i, n;
 417
 418 #define f_bogus 1u
 419
 420   cw.f = 0;
 421
 422   ego(argv[0]);
 423   sel_init(&sel);
 424   for (;;) {
 425     static struct option opt[] = {
 426       { "help",                 0,              0,      'h' },
 427       { "version",              0,              0,      'v' },
 428       { "usage",                0,              0,      'u' },
 429       { "listen",               OPTF_ARGREQ,    0,      'l' },
 430       { "peer",                 OPTF_ARGREQ,    0,      'p' },
 431       { "bind",                 OPTF_ARGREQ,    0,      'b' },
 432       { "connect",              OPTF_ARGREQ,    0,      'c' },
 433       { 0,                      0,              0,      0 }
 434     };
 435     int i;
 436
 437     i = mdwopt(argc, argv, "hvul:p:b:c:", opt, 0, 0, 0);
 438     if (i < 0)
 439       break;
 440     switch (i) {
 441       case 'h': help(stdout); exit(0);
 442       case 'v': version(stdout); exit(0);
 443       case 'u': usage(stdout); exit(0);
 444       case 'l': bindsvc = optarg; break;
 445       case 'p': DA_PUSH(&peerhosts, optarg); break;
 446       case 'b': DA_PUSH(&bindhosts, optarg); break;
 447       case 'c': connhost = optarg; break;
 448       default: f |= f_bogus; break;
 449     }
 450   }
 451   if (optind + 2 != argc || (f&f_bogus)) { usage(stderr); exit(1); }
 452
 453   if (DA_LEN(&bindhosts) && !bindsvc && !connhost)
 454     die(1, "bind addr only makes sense when listening or connecting");
 455   if (DA_LEN(&peerhosts) && !bindsvc)
 456     die(1, "peer addr only makes sense when listening");
 457   if (bindsvc && connhost)
 458     die(1, "can't listen and connect");
 459
 460   aihint.ai_family = AF_INET;
 461   DA_CREATE(&cw.me); DA_CREATE(&cw.peer);
 462
 463   n = DA_LEN(&bindhosts);
 464   if (n || bindsvc) {
 465     aihint.ai_socktype = SOCK_STREAM;
 466     aihint.ai_protocol = IPPROTO_TCP;
 467     aihint.ai_flags = AI_ADDRCONFIG | AI_PASSIVE;
 468     if (!n) {
 469       parseaddr(&aihint, 0, bindsvc, 0, &ailist);
 470       pushaddrs(&cw.me, ailist);
 471       freeaddrinfo(ailist);
 472     } else if (!bindsvc) {
 473       if (n != 1) die(1, "can only bind to one address as client");
 474       parseaddr(&aihint, DA(&bindhosts)[0], 0, 0, &ailist); ai = ailist;
 475       initaddr(&bindaddr);
 476       copyaddr(&bindaddr, ai->ai_addr, caf_addr);
 477       freeaddrinfo(ailist);
 478     } else for (i = 0; i < n; i++) {
 479       parseaddr(&aihint, DA(&bindhosts)[i], bindsvc, 0, &ailist);
 480       pushaddrs(&cw.me, ailist);
 481       freeaddrinfo(ailist);
 482     }
 483     if (bindsvc) {
 484       cw.f |= cwf_port;
 485       n = DA_LEN(&cw.me);
 486       cw.sfv = xmalloc(n*sizeof(*cw.sfv));
 487     }
 488   }
 489
 490   n = DA_LEN(&peerhosts);
 491   if (n) {
 492     aihint.ai_socktype = SOCK_STREAM;
 493     aihint.ai_protocol = IPPROTO_TCP;
 494     aihint.ai_flags = AI_ADDRCONFIG;
 495     for (i = 0; i < n; i++) {
 496       parseaddr(&aihint, DA(&peerhosts)[i], 0, 0, &ailist);
 497       pushaddrs(&cw.peer, ailist);
 498       freeaddrinfo(ailist);
 499     }
 500   }
 501
 502   if (connhost) {
 503     aihint.ai_socktype = SOCK_STREAM;
 504     aihint.ai_protocol = IPPROTO_TCP;
 505     aihint.ai_flags = AI_ADDRCONFIG;
 506     parseaddr(&aihint, connhost, 0, paf_parse, &ailist);
 507
 508     for (ai = ailist; ai; ai = ai->ai_next) {
 509       if ((fd = socket(ai->ai_family, SOCK_STREAM, IPPROTO_TCP)) >= 0 &&
 510           (!DA_LEN(&bindhosts) ||
 511            !bind(fd, &bindaddr.sa, addrsz(&bindaddr))) &&
 512           !connect(fd, ai->ai_addr, ai->ai_addrlen))
 513         goto conn_tcp;
 514       if (fd >= 0) close(fd);
 515     }
 516     die(1, "couldn't connect to TCP server: %s", strerror(errno));
 517   conn_tcp:
 518     if (nonblockify(fd) || cloexec(fd))
 519       die(1, "couldn't connect to TCP server: %s", strerror(errno));
 520   }
 521
 522   aihint.ai_socktype = SOCK_DGRAM;
 523   aihint.ai_protocol = IPPROTO_UDP;
 524   aihint.ai_flags = AI_ADDRCONFIG | AI_PASSIVE;
 525   parseaddr(&aihint, argv[optind], 0, paf_parse, &ailist); ai = ailist;
 526   if ((fd_udp = socket(ai->ai_family, SOCK_DGRAM, IPPROTO_UDP)) < 0 ||
 527       nonblockify(fd_udp) || cloexec(fd_udp) ||
 528       setsockopt(fd_udp, SOL_SOCKET, SO_RCVBUF, &len, sizeof(len)) ||
 529       setsockopt(fd_udp, SOL_SOCKET, SO_SNDBUF, &len, sizeof(len)) ||
 530       bind(fd_udp, ai->ai_addr, ai->ai_addrlen))
 531     die(1, "couldn't set up UDP socket: %s", strerror(errno));
 532   freeaddrinfo(ailist);
 533   aihint.ai_flags = AI_ADDRCONFIG;
 534   parseaddr(&aihint, argv[optind + 1], 0, paf_parse, &ailist);
 535   for (ai = ailist; ai; ai = ai->ai_next)
 536     if (!connect(fd_udp, ai->ai_addr, ai->ai_addrlen)) goto conn_udp;
 537   die(1, "couldn't set up UDP socket: %s", strerror(errno));
 538 conn_udp:
 539
 540   if (bindsvc) dolisten();
 541   else if (connhost) dofwd(fd, fd);
 542   else dofwd(STDIN_FILENO, STDOUT_FILENO);
 543
 544   for (;;) {
 545     if (sel_select(&sel) && errno != EINTR)
 546       die(1, "select failed: %s", strerror(errno));
 547   }
 548   return (0);
 549 }
 550
 551 /*----- That's all, folks -------------------------------------------------*/